Thursday, July 05, 2007

Belief Persistence (paca)

Written Wyrdd had an interesting post today about confirmation bias on her blog. In brief, it is the tendency to seek out information which confirms a belief and avoid or discount any contrary evidence. I happened to be reading last night about a related, but slightly different, bias in judgement called Belief Persistence. Here's one of the experiments that gives us evidence for the phenomenon.

An experimenter tells a research participant that they are going to be asked to judge which suicide notes in a list are real and which were made up by psych students. The participant goes through and moves the suicide notes into two stacks based on whatever criteria they like. Afterwards, the experimenter looks at the result and then tells the participant if they did very well in discerning the real notes, if they did quite poorly, or if they just did average. The participant then nods their head.

However, at this point, the researcher reveals that the evaluation they just gave was completely made up. The participant was assigned to a good, average, or bad group before they ever walked in the door. The supposed evaluation therefore has no relationship at all to how they did. The researcher even shows them the instructions they had and how they were assigned to a meaningless group.

In the final step before the participant leaves, the participant is then asked how good they think they are at judging suicide notes. Here's the belief persistence.... Even though the researcher just told them that their assigned rating was meaningless and had no relationship to how good or bad they are, the participants typically rate themselves as good, average, or bad just as they had been falsely told a couple minutes earlier. So the participant continues to believe the evaluation they received even when they know the evaluation was meaningless.

This is an important finding for designing psychology experiments as it is not too uncommon to tell some participants some really weird or even traumatic things, but then later debrief them that they were false. However, if belief persistence is right, that's really not good enough. The participant might keep on believing those weird facts despite the follow-up explanation.

It's of course also important for understanding how we think in general. It reminds me at the moment of the dangers of teasing. When a parent teases their child about something, the child is likely to continue believing it even when the same parent takes the time to explain that it was just a joke.


bunnygirl said...

When a parent teases their child about something, the child is likely to continue believing it even when the same parent takes the time to explain that it was just a joke.

Too bad you weren't around to tell that to my parents when I was growing up. I was a sensitive kid and my stepmother thought she was "toughening me up" by teasing me.

And she wonders how I ended up with teenage self-esteem issues and why I have little to do with her today. Right.

Belief persistence and confirmation bias are really interesting things to study and have to be taken into consideration in all kinds of research arenas, even questionnaires. It's quite amazing, when you think about it.

Sammy Jankis said...

Carrying this on in the realm of children, if you actually walk to the closet and open the door, or actually get on the floor and look under the bed to confirm that there are no monsters, you've just confirmed in the child's mind that monsters exist because you had to go check this time.

Man I miss psych classes!

writtenwyrdd said...

Good points! When I was two, I was going through a major phase of asking the same question fifty thousand times a day, because one answer just wouldn't do. So, after asking mom, "Where do I come from?" all day long, she suddenly loses her practically infinite patience and says, "I found you under a rock, alright? Now can I please have five minutes to finish what I'm doing?"

So she found me crying my little two-year-old eyes out about ten minutes later. Asks why I was crying, and I said, "You found me under a rock!" THAT I could actually absorb.

I'm scarred for life, I tell ya. No wonder I write science fiction. The aliens put me under the rock and she found me. LOL.